Conventionally, as an intake air amount control system for an internal combustion engine, provided for controlling an intake air amount, one described in Patent Literature 1 is known. This engine includes a variable valve lift mechanism and a variable cam phase mechanism, and the valve lift of intake valves is changed by the variable valve lift mechanism, and the cam phase of an intake cam shaft relative to a crankshaft is changed by the variable cam phase mechanism, whereby the valve timing of the intake valve is varied.
In this intake air amount control system, the cam phase and the valve lift of each intake valve are both variably controlled by the variable cam phase mechanism and the variable valve lift mechanism, whereby the intake air amount is controlled. More specifically, a target valve lift, which is a target value of the valve lift, and a target cam phase, which is a target value of the cam phase, are set according to load on the engine and the like, and feedback control is carried out based on the target values. Further, the target cam phase or the target valve lift is corrected so as to avoid interaction between the intake valve and a piston. More specifically, for example, the difference between a valve lift detected by a sensor and the target valve lift is compared with a predetermined threshold value, and when the difference is equal to or larger than the threshold value, the target cam phase is corrected such that it is more retarded (example shown in FIG. 10 in Patent Literature 1).
[Patent Literature 1] Japanese Laid-Open Patent Publication (Kokai) No. 2002-332876